Zeroizing means for indicating mechanisms



Maiy 20, 1941. FiHORTON 2,242,355

ZEROIZING MEANS FOR INDICATING MECHANISMS Filed March 4, 1940 Patented May 20, 1941 ZEROIZING IVIEAN S FOR INDICATING MECHANISMS Frank Horton, London, England, assignor to Foreign Rights London, England (Precision Meters) Limited,

Application March 4, 1940, Serial No. 322,199 In Great Britain March 6, 1939 2 Claims.

This invention relates to zeroizing means for indicating mechanism, used, for example, in connection with liquid meters such as those employed in the dispensing of petrol or lubricating oils, in which the indicating means includes a hand or hands adapted to be traversed over a dial for indicating the amount delivered.

.With such apparatus before subsequent operation of the meter it is necessary to return the hand or hands to zero. This return to zero is effected manually by means of a finger knob provided on the zeroizing spindle of the mechanism.

It will be appreciated that by rough usage of the zeroizing knob the hand and/or the indicating mechanism may be injured or displaced, resulting in inaccurate indications, and it is an object of the invention to provide an improved construction of zeroizing means whereby such injury to the indicating hand or mechanism is avoided. Another object is to provide means whereby the friction between the knob and the hands and/or the indicating mechanism is reduced to a minimum.

According to the invention clutch means are provided between the zeroizing knob and the zeroizing spindle of the indicating mechanism which are adapted to be efiective under normal usage, to rotate the spindle in a direction to zeroize the indicating hand, but which are adapted to be inefiective in the event of the knob being jerked or rotated above a predetermined The clutch preferably comprises means adapted to become displaced by centrifugal action should the knob be moved or jerked at a rate above a predetermined speed.

The clutching of the knob to the spindle is preferably efiected through the medium of steel balls adapted to lodge between opposing walls on the clutch parts.

The knob comprises one clutch part and may be mounted upon the other clutch part by means of anti-frictional ball means which are arranged to prevent relative axial movement.

In the accompanying drawing:

Figure 1 is a sectional elevation of the knob mounted upon a spindle;

Figure 2 is a plan with part of the knob removed to show the clutch;

Figure 3 is an elevation partly in section at right angles to Figure 1.

In carrying the invention into effect according to one convenient mode the zeroizing knob is formed with an inner chamber I adapted to contain a one-way clutch device, one member 2 of which is mounted upon the zeroizing spindle 3 of the indicating mechanism which spindle projects into the chambered knob.

The knob may be constructed in two parts, an outer cupped part 4 and an inner part 5 which forms the other clutch member and which is provided with a sleeve portion 6 by which it is freely mounted upon the first-mentioned clutch part 2 associated with the zeroizing spindle. This clutch part is provided with a screwed sleeve I by which it is mounted on the spindle 3, such sleeve providing a bearing for the inner part of the knob. The inner'part 5 of the knob and the associated part of the clutch sleeve 1 are formed as ball races to accommodate a row of steel balls 8 whereby the knob is mounted on the clutch sleeve.

The clutch member 2 at its outer end is provided with an axial extension 9 adapted to engage with a working fit in a recess I0 in the outer part 4 of the knob, a steel ball H being provided within the recess for engagement by said axial extension. This latter ball ll takes up any inward thrust upon the knob, while the above-mentioned ball race 8 resists outward movement.

The clutch part 2 mounted upon the zeroizing spindle is provided with a plurality of peripheral recesses l2, for example three, while the inner part 5 of the knob, where it surrounds this clutch part, is provided with two diametrically opposite recesses l3. These recesses l3 accommodate two steel balls 14 which form the connecting means between the clutch parts when it is desired to impart a rotary movement to the spindle to zeroize the hand or pointer of the indicating mechanism, the arrangement being such that a connection is formed when the ball enters a peripheral recess 12 in the clutch part as indicated at the upper part of Figure 2. The depth of the recesses I2 i approximately equal to the diameter of the balls l4 so that the ball is gripped along a diameter between the wall of the recess I! of the clutch part and the wall of the appropriate diametrical recess l3 in the inner sleeve part of the knob.

The clutch is adapted to form a driving connection between the knob and spindle when the knob is turned to the left under normal usage for zeroizing.

In the event of the knob being jerked or spun at a relatively high speed in a counterclockwise direction as seen in Figure 2, the balls I4 leave the peripheral recesses ll of the clutch part 2 and under the action of centrifugal force enter the diametrical recesses 53 in the inner part of the knob so that there is no driving connection between the clutch part and the knob. Movement of the knob in a clockwise direction will be free owing to the clutch being a one-way clutch.

The inner and outer parts 5 and 4 of the knob are connected together by any suitable means such as screws l5 and the outer part of the knob is provided with a milled ridge whereby it may be gripped for operation.

I claim:

1. Zeroizing means for indicating mechanism having a Zeroizing spindle, comprising a knob, clutch means between the knob and spindle for rotating the spindle by the knob, said knob comprising inner and outer part, means for securing said parts together, the inner part forming one element of the clutch and surrounding the other element of the clutch which is secured to said spindle, said inner part being provided with diametrical recesses, clutch balls in said recesses,-

said clutch element fixed in the spindle being provided with tapered peripheral recesses forming shoulders adapted for engagement by the balls to form a driving connection.

2. Zeroizing means as claimed in claim 1, wherein a ball race is provided between the inner part of the knob and the element of the clutch fixed to the spindle, said element having an axial extension, the outer part of the knob having a recess in which said axial extension is located, and a ball located in said recess between the end thereof and said extension.

FRANK HORTON. 

